/**
 * 发送get异步请求
 * @param {string} url  请求地址
 * @param {object} params 请求参数
 * @param {string|undefined} type 返回的数据类型 
 * @param {object} headers 自定义请求头
 * @returns 
 */
function get(url,params,type,headers = {}){
    const p = new Promise((resolve,reject) => {
        const xhr = new XMLHttpRequest
        xhr.onreadystatechange = () => {
            if(xhr.readyState === 4){
                if(xhr.status === 200){
                    let res = xhr.responseText
                    if(type === "json") res = JSON.parse(res)
                    resolve(res)
                }else{
                    reject(xhr.status)
                }
            }
        }
        let temp = [];
        for(let key in params){
            temp.push(`${key}=${params[key]}`)
        }
        xhr.open("get",`${url}?${temp.join("&")}`);
        for(let key in headers){
            xhr.setRequestHeader(key,headers[key])
        }
        xhr.send(null)
    });

    return p;
}



/**
 * 发送post异步请求
 * @param {string} url  请求地址
 * @param {object} params 请求参数
 * @param {string|undefined} type 返回的数据类型 
 * @param {object} headers 自定义请求头
 * @returns 
 */
 function post(url,params,type,headers = {}){
    const p = new Promise((resolve,reject) => {
        const xhr = new XMLHttpRequest
        xhr.onreadystatechange = () => {
            if(xhr.readyState === 4){
                if(xhr.status === 200){
                    let res = xhr.responseText
                    if(type === "json") res = JSON.parse(res)
                    resolve(res)
                }else{
                    reject(xhr.status)
                }
            }
        }
        let temp = [];
        for(let key in params){
            temp.push(`${key}=${params[key]}`);
        }
        xhr.open("post",url);
        xhr.setRequestHeader("content-type","application/x-www-form-urlencoded")
        for(let key in headers){
            xhr.setRequestHeader(key,headers[key])
        }
        xhr.send(temp.join("&"))
    });

    return p;
}